@mixin textblock($width, $height, $size, $color, $lineheight: $height) {
    @if $width {
      width: $width;
    }
    @if $height {
      height: $height;
    }
    @if $size {
      font-size: $size;
    }
    @if $color {
      color: $color;
    }
    @if $width {
      width: $width;
    }
    line-height: $lineheight;
}
@mixin button($width, $height, $size, $color, $lineheight, $backcolor: null, $radius: null) {
    @include textblock($width, $height, $size, $color, $lineheight);
    @if $backcolor {
        background-color: $backcolor;
    }
    @if $radius {
        border-radius: $radius;
    }
    text-align: center;
    cursor: pointer;
}
@mixin icon($width,$height,$top,$left,$src){
    position: relative;
    &:after{
        content: '';
        position: absolute;
        left: $left;
        top: $top;
        width: $width;
        height: $height;
        display: block;
        background: url($src) no-repeat center/contain;
    }
}
$blue: #0088ff; // 产品色
$black: #303133;// 标题色
$gray: #909399; // 内容色